High temperature furnace conveyor



J- A. MURPHY June 11, 1968 HIGH TEMPERATURE FURNACE CONVEYOR 2 Sheets-Sheet 1 Filed March 22, 1966 mwJOOQ INVENTOR.

JAMES A. MURPHY RM Y June 1 1, 1968 Y .1. A. MURPHY 3,387,835

HIGH TEMPERATURE FURNACE CONVEYOR Filed March 22, 1966 2 Sheets-Sheet 2 INVENTOR.

JAMES A. MURPHY Unite ABSTRACT OF THE DISCLOSURE A conveyor belt assembly for a high temperature furnace comprises a first endless belt having an upper flight extending entirely through the furnace, a second endless belt at the inlet side of the furnace having a top flight extending into the furnace alongside and at a higher level than the adjacent end of the upper flight of the first belt and a third endless belt at the discharge end of said furnace extending adjacent and alongside the other end of the first belt, there being a first article transfer point wherein the upper flights of the inlet and through belts interchange levels and a second article transfer point wherein the upper flights of the discharge and through belts interchange levels, and all belts being independently driven at selected relative speeds.

This invention relates to a high temperature furnace and particularly to conveyor arrangement for the controlled passage of material to be heat treated through the furnace.

In high temperature furnaces such as contemplated by the invention an article or group of articles is moved through an electrically heated zone wherein the article or articles are subjected to heat in the range of 2,000 C. or more. In known furnaces the article may be advanced through the furnace on a continuous heat resistant belt or is pushed through along a suitable guide, but while these arrangements are capable of overall speed control they do not afford such control of the article passage as would enable articles in different positions of passage through the furnace to move at different speeds for obtaining different heating or cooling steps during the treatment, and it is the major object of this invention to overcome these disadvantages and deficiencies of the prior art.

It is a further object of the invention to provide a novel high temperature furnace wherein an article passing through the furnace may automatically change its speed of movement through the furnace as it passes along a path between different treatment zones.

A further object of the invention is to provide a novel high temperature furnace wherein a special arrangement of inter-related conveyor belts automatically provides for different speeds of movement of an article during passage through the furnace.

Further objects of the invention will appear as the description proceeds in connection with the appended claims and the annexed drawings wherein:

FIGURE 1 is a side elevation, partly in section and partly diagrammatic, illustrating the invention according to a preferred embodiment;

FIGURE 2 is a generally perspective view showing the multiple belt arrangement apart from furnace structure to aid in the description of the invention; and

FIGURE 3 is a relatively diagrammatic representation in side elevation partly in section showing the conveyor belt association at the transfer points.

A high temperature electric furnace 10 is mounted on a suitable supporting structure 11 uprising from the floor. The furnace comprises a tunnel 12 through which articles to be heat treated are moved in such manner that a single States Patent "ice traverse of the furnace will accomplish the desired treatment operation. In the disclosed embodiment the articles to be heat treated are disposed in one or more open top trays 13 conveyed in a special manner through the furnace.

Electrical energy is imparted in a known manner to the furnace heating unit at 14 which contains for example an induction unit surrounding the tunnel and capable of raising the temperature within the heating zone indicated at 15 to about 2,000 C. or more if desired.

A correlated endless belt system conveys trays 13 through the furnace. This system comprises an endless belt 16 which preferably extends the entire length of the furnace. At the intake end of the furnace, belt 16 is flanked at opposite sides by two similar parallel endless belts 17 and 18 that extend at least into and usually through much of the heating zone 15. At the discharge end of the furnace, belt 16 is flanked at opposite sides by two similar parallel endless belts 19 and 21 that are longitudinally aligned with belts 17 and 18 respectively.

As shown in FIGURE 1, the top flight 22 of belt 16 extends substantially horizontally longitudinally from end to end of the furnace, flight 22 being supported at opposite ends by rollers 23 at the same level. Belt 16 is driven at a selected speed by a feed roller indicated at 24 and driven by a motor or the like indicated at 24, and is otherwise supported and guided by a series of other rollers 25.

Belt 18 has a top flight 26 that extends substantially horizontally longitudinally between support rolls 27 and 23, and belt 18 is driven by a feed roll 29 rotated by a motor or the like indicated at 29 at a selected speed independently of feed roll 24. Otherwise belt 18 is suitably supported and guided by rolls 31.

Belt 17 is similar in all respects to belt 18 except that it is arranged on the opposite side of belt 16 as shown in FIGURE 2, and upper flight 32 of belt 17 is of the same length as, disposed at the same level as and driven at the same linear speed as upper flight 26 of belt 18.

Belts 17 and 18 are preferably arranged closely adjacent opposite edges of belt 16 but far enough away to avoid contact therewith during operation.

Belt 21 has a top flight 33 that starts closely adjacent the right end of belt flight 26, and extends longitudinally substantially horizontally between support rolls 34 and 35 in alignment with belt 18. Belt 21 is driven at a de sired speed by a feed roll 36 that is driven by a motor or the like indicated at 36' independently from rolls 24 and 29, and it is supported and guided by suitable other rolls 37.

Belt 19 is similar in all respects to belt 21 except that it is on the opposite side of belt 16 as shown in FIGURE 2, and it has a top flight 38 of the same length as, disposed at the same level as and driven at the same linear speed as upper flight 33 of belt 21.

In the foregoing assembly feed roller 24 is driven by a suitable variable speed mechanism (not shown). Usually a common feed roller 29 drives both belts 17 and 18 at the same variable speed. Similarly a common feed roll 36 drives both belts 19 and 21 at the same variable speed.

Tray 13 is wide enough to span the parallel outer belts 17 and 18, and 19 and 21. Usually the outer belts are narrower than the inner belt. For example, all belts may be of flexible woven high temperature resistant metal mesh, with the inner belt about twice as wide as the outer belts.

At the left or intake side of FIGURE 1 outer belt flights 26 and 32 are disposed at a slightly higher level than inner belt flight 22, but at a transfer point indicated at 41 which may be near the exit end of the high heating zone in the tunnel this condition is reversed so that an intermediate section 42 of inner belt 16 is disposed above the level of the outer belts. At a succeeding transfer point indicated at 43 the respective belt levels are again reversed and upper flight 22 of belt 16 becomes now disposed below the level of outer belt top flights 33 and 38.

Thus a tray 13 containing articles to be heat treated is placed as shown in FIGURE 1 to bridge the upper flights of outer belts 17 and 18 whereby it is advanced toward and into the heating zone 15 at a desired speed selected according to the operation being performed, At transfer point 41, due to the change in belt levels, tray 13 leaves belts 17 and 18 and transfers onto inner belt 16 alone which is usually moving at a different speed corresponding to a different treatment phase.

This change in belt level to effect transfer of tray 13 may be accomplished by suitable belt deflection members extending transversely in fixed locations along the furnace; Three of these members 44, 45 and 46 are indicated for example in FIGURE 3 where it will be seen that belt 18 (and 17), at transfer point 41, is deflected downwardly over member 44 and beneath member 45 to pass over support roller 28 which is preferably located at the same vertical level as rollers 23 for belt 16, This provides a gradual downward and forward slope section on outer belts 17 and 18, indicated at 47 in FIGURE 3. At the same time, at transfer point 41, inner belt 16 is deflected upwardly, passing under member 44 and over member 45 in an upward and forward slope section indicated at 48 in FIGURE 3.

As may 13 enters transfer point 41, its leading edge encounters the relatively upwardly sloping surface 48 of belt 16 and gradually its lower surface becomes fully engaged by slope 48 until the moving tray 13 is lifted off the outer belts and continues to move forwardly without interruption, but now upon and at the speed of belt 16 alone.

For example, it may be desirable as a condition of the process at hand that the tray 13 move between transfer points 41 and 43 at a slower speed than through the heating zone 15 to provide a buffer zone 48 wherein the applied heat gradually reduces and the article or articles in the tray gradually normalize for a given time. In that case belt 16 would move at a linear speed correspondingly less than belts 17 and 18.

The angle of relative slope of the belt surfaces at 47 and 48 is not particularly critical, but it must be a fairly small angle with the horizontal so that the transfer is not jerky or abrupt but is effected gradually and smoothly without jarring the tray 13. Any suitable angle up to about 30 is norm-ally acceptable depending upon the belt structure and space considerations.

As tray 13 enters transfer point 43, its leading edge encounters the rising sloped surface sections 51 of outer belts 19 and 21 while at the same time the upper flight of inner belt 16 passes over the rear edge of member 45 and slopes downwardly under member 46 to provide the oppositely sloped surface section 52 on belt 16, whereby moving tray 13 is lifted off belt 16 and becomes supported by and moved along without interruption by outer belts 19 and 21. This transfer is gradual and smooth as at transfer point 41.

It will be noted that support roll 35 is prefenably disposed at the same level as support roll 27 so that the tray 13 leaves the furnace at the same level that it enters.

In FIGURE 1 transfer point 43 is shown as located at the intake end of a cooling zone 53 of the furnace wherein a water jacket 54 enclosed the tunnel and effects rapid cooling of the articles in tray 13. This cooling rate may be desirably timed by so driving roll 36 to effect linear advance of belts 17 and 19 to move tray 13 either slower or faster than it moved through the bufier zone.

Any combination of variable speed belt drives may be used to suit the process at hand. In n satisfactory embodiment of the invention through belt 16 is arranged to be driven in the range between 0.125" per minute and 2.45 per minute. The inlet pair of belts 17, 18 may be driven in two ranges, a slow range between 0.89 per minute and 17.1" per minute and a fast range between 18.8 per minute and 360" per minute. The discharge pair of belts 19, 21. may be driven in two ranges, a slow range be tween 0.125 per minute and 2.45 per minute and a fast range betwen 4.7 per minute and per minute.

The invention may be embodied in other specific forms without departing from the spirit or essential character istics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims mther than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is:

1. In a high temperature furnace assembly, means for controllably moving an article to be heat treated therethrough comprising a conveyor belt assembly having longitudinally spaced sections adapted to advance the article at different linear speeds and means for automatically effecting transfer of the moving article between said sections during passage through said furnace assembly, said conveyor belt assembly comprising an endless belt means having an upper flight extending entirely through the furnace, endless belt means at the inlet side of the furnace having a top flight extending into the furnace alongside and at a higher level than the adjacent end of the upper flight of said through belt means and endless belt means at the discharge end of said furnace extending adjacent and alongside the other end of said through belt means, and said means for effecting transfer of the moving article comprising means defining a first transfer point wherein the upper flights of said inlet and through belt means interchange levels and means defining a second transfer point wherein the upper flights of said discharge and through belt means interchange levels.

2. In the furnace defined in claim 1, said through belt means being a single endless belt, and said inlet and discharge belt means each comprising a pair of endless belts arranged in parallel relation on opposite sides of said through belt, the inlet and discharge belts on opposite sides of said through belt being longitudinally aligned.

3. In the furnace defined in claim 2, said through belt being appreciably wider than any of said other belts.

4. In the furnace defined in claim 3, said through belt being about twice as wide as each of said other belts.

5. In the furnace defined in claim 1, independent variable speed drive means for each of said belt means.

6. In the furnace defined in claim 1, said first transfer point being located near the discharge end of a high heating zone of said furnace, and the space between said first and second transfer points being mainly a bufier zone wherein the article leaves the high heat zone.

7. In the furnace defined in claim 6, means for positively cooling the article after passage through said sec.

ond transfer point.

References Cited UNITED STATES PATENTS 1,489,926 4/ 1924 Burtchaell 198-76 XR 2,409,298 10/1946 Merrill 3466 2,677,336 5/1954 Spooner 34-66 XR 3,072,095 1/1963 Keessen et al. 198-76 XR FOREIGN PATENTS 747,317 4/ 1956 Great Britain.

FREDERICK -L. MATTESON, 1a., Primary Examiner.

A. D. HERRMANN, Assistant Examiner. 

